A thin film transistor liquid crystal display (TFT-LCD) is a comparatively ideal display device due to advantages of small size, low power consumption, no radiation and so on. In recent years, the scope of application of TFT-LCDs in the display field is gradually enlarged, and relevant technologies are developed rapidly. Displays of a high aperture ratio Advanced-super Dimensional Switching (HADS) mode have been widely applied to various display products due to advantages of wide viewing angle, low color cast and so on.
As shown in FIG. 1, an array substrate of an HADS technology in the state of art comprises a base substrate 1a, a gate electrode 2a, a common electrode line 3a, a gate insulating layer 4a, an active layer 5a, a pixel electrode 6a, a drain electrode 8a, a source electrode 7a, a data line 9a, a passivation layer 10a, and a common electrode 11a; the common electrode 11a is electrically connected with the common electrode line 3a through a via hole 20a. It can be seen from FIG. 1, the via hole 20a is a via hole penetrating through both the gate insulating layer 4a and the passivation layer 10a. When the array substrate is designed, in order to reduce coupling capacitance between the common electrode 11a and the data line 9a, the passivation layer 10a is required to be made thicker, and therefore, to ensure effectiveness of the via hole 20a, a hole depth of the via hole 20a is enough large and the size of the via hole is relatively large. However, the relatively large hole depth and size of the via hole 20a make the coating process of a subsequent fabricating process be difficulty controlled and easily invoke moires on a coated film layer, thereby affecting the yield of the fabricated array substrates.